THE SUPERIOR CAVAL SYSTEM. 



88i 



In connection with the abundant variation shown in the size of the external jugular it is 

 interesting to note that in the majority of mammals it is the most important vein of the neck, 

 surpassing the internal jugular in size. It is, however, of later development than the latter, 

 and its later importance is due largely to the union with it of the facial vein or of the 

 linguo-facial trunk. In man, however, a new "connection of the facial with the internal jugular 

 occurs, whereby the importance of the external jugular becomes reduced, and its variation 

 in size is largely dependent upon the extent to which the original direct connection of 

 the facial with it is retained. 



Fig. 759. 



Temporal fasc 



Superficial 



temporal vein 



Middle temporal- 



Occipital vein- 

 Internal maxillary 

 vein 



Temporo- 

 maxillary vein 

 Posterior auricular' 

 vein 



Sterno-cleido- 

 mastoid 



Communication 



between facial 



and external 



jugular vein 



External jugular 

 vein 

 Tributary of trans- 

 verse cervical vein 

 Posterior external 

 jugular vein 



Trapezius 



^... 



Frontal veins 



Supraorbital vein 

 Branch of communi- 

 cation with ophthal- 

 mic vein 

 Angular vein 



Lateral nasal vein 



Facial vein 



Deep facial vein 



Submental vein 

 Common facial vein 



Superficial veins of head and neck ; external jugular lies beneath platysma 

 muscle, which has been partly removed. 



Practical Considerations. — The line of the external jugular vein is from the 

 angle of the jaw to the centre of the clavicle. Backward pressure made about 

 an inch above the latter point will cause the vein to become visible through- 

 out its length. For that reason it was at one time selected for phlebotomy in 

 congestions or inflammations about the face and neck. The vein is in the 

 superficial fascia and therefore courses over the sterno-mastoid muscle. In ail 

 operations on the side of the neck its size and its course should be borne in mind. 



